Now that we have established identity of cytochalasin B binding Site I protein to the glucose carrier, we will use this particular cytochalasin B binding activity as a marker for the carrier. Our 0.5 percent Triton X-100 fraction of the membrane proteins still includes several peptides such as Bands 3, 4.1, 4.2, 4.5 and a faint band at 2.1; it is far yet to come up with a single peptide as Site I-protein. The assay of Site I-binding protein is being well established and relatively simple. Various protein separation techniques now available will be used to purify the binding activity. These include adsorption chromatographies, molecular sieve chromatographies and affinity chromatographies, and combination of them. Chemical synthesis of cytochalasin B which contains reactive group (for covalent rection with proteins) will be continued. This will be used for tagging the Site I-protein as an alternative approach to the isolation and purification of this protein. Once the Site I-protein was obtained in a reasonably pure form, functional reconstitution of the glucose transport from this protein will be attempted. A spherical black membrane preparation of a large surface area which we have originally reported, will be used for such reconstitution studies. The reconstitution in this particular preparation will provide unequivocal demonstration of the carrier function based on quantitative flux measurements and kinetic characterizations. BIBLIOGRAPHIC REFERENCES: Chan Y. Jung and Basab K. Mookerjee: Inhibitory effect of furosemide on glucose transport. J. Clin. Lab. Med. 87, 960-966, 1976. Floyd A. Green and Chan Y. Jung: Cold-induced hemolysis in a hypertonic milieu. J. Membrane Biol. In Press: Chan Y. Jung and Rampal, Amrit L (1977) Cytochalasin B binding proteins and glucose carrier in human erythrocyte membrane. J. Biol. Chem.